The observation object defining a region to track.
- iOS 11.0+
- macOS 10.13+
- tvOS 11.0+
Providing an observation not returned from a tracker, such as a user-defined observation, begins a new tracker for the sequence. Providing an observation that was returned from a tracker continues the use of that tracker, to track the region to the next frame.
In general, unless specified in the request's documentation or header file, you must define the rectangle in normalized coordinates, with the origin at the lower-left corner.